Pyrimidinediones (PYD) are highly potent small molecule inhibitors that have a dual anti-HIV mechanism of action: viral entry inhibition and non-nucleoside reverse transcriptase inhibition (NNRTI). The PYD compounds have shown in vitro subnanomolar levels of activity as an NNRTI and nanomolar levels of activity as inhibitors of entry occurring prior to chemokine receptor binding and fusion. However, as microbicides compounds are being developed, delivery issues that are part of the formulation of the compound have lagged behind causing a critical delay in product development. Due to low solubility and poor penetration through the mucosa to the target site of action, Pyrimidinediones face significant obstacles as microbicides. Strategic drug delivery design is essential for Pyrimidinediones to advance as viable microbicide products. We propose a combination of innovative drug delivery strategies to enhance PYD anti-HIV efficacy through polymer biochemistry formulations. Specifically, nanoparticle encapsulation has been used to overcome many of the challenges presented when using hydrophobic drug molecules; however, its use as a vaginal drug delivery system has not been investigated. In the R21 phase of this project, we propose to develop nanoparticle encapsulation of PYD as a novel drug delivery method to improve the potency of HIV inhibition activity by increasing long term drug release, protecting against enzymatic degradation, enhancing submucosal tissue penetration and cell localization. Additionally, we propose to further formulate the nanoparticle PYD formulation into a vaginally delivery polymer film dosage form. Such quick dissolving solid dosage forms have recently been proposed as a innovative alternative to address several acceptability and compliance issues observed in more traditional vaginal delivery systems (gels, creams, intra-vaginal rings). Our nanoparticle PYD film delivery approach offers several innovative advantages in microbicide development by suggesting enhanced apparent activity without active pharmaceutical ingredient (API) reformulation, conferring HIV protection over long periods of time through controlled drug release, making such a microbicide coitally-independent, and introducing a novel drug delivery method through vaginal films that addresses many of the acceptability issues with gels and other semi-solid dosage forms. Biological characterization and evaluation will be preformed to confirm the efficacy of PYD nanoparticles in biologically relevant conditions. The encapsulation of PYD into biodegradable nanoparticles will be characterized and evaluated in specifically designed in vitro assays to determine drug targeting and release. Additionally, the anti-HIV efficacy of the nanoparticle PYD will be compared to unformulated PYD in biologically relevant in vitro assays to determine the optimal formulation. Finally, the formulation will be introduced into a solid vaginal film dosage form to evaluate its biological properties in HIV prevention.